add design-add-and-search-words-data-structure

Author: i-mprovising

design-add-and-search-words-data-structure/i-mprovising.py

@@ -0,0 +1,44 @@
+"""
+Time complexity O(26^w)
+Space complexity O(w)
+
+Trie, DFS
+"""
+
+class Node:
+    def __init__(self, end=False):
+        self.children = {} # char : node
+        self.end = end
+
+class WordDictionary:
+
+    def __init__(self):
+        self.root = Node(end=True)
+        
+    def addWord(self, word: str) -> None:
+        node = self.root
+        for ch in word:
+            if ch not in node.children:
+                node.children[ch] = Node()
+            node = node.children[ch]
+        node.end = True
+
+    def search(self, word: str) -> bool:
+        return self.dfs(self.root, word)
+
+    def dfs(self, start, word):
+        ch = word[0]
+        if ch == word:
+            if ch == '.':
+                return any([node.end for c, node in start.children.items()])
+            elif ch in start.children:
+                if start.children[ch].end:
+                    return True
+            return False
+        
+        if ch == '.':
+            return any([self.dfs(node, word[1:]) for c, node in start.children.items()])
+        elif ch in start.children:
+            return self.dfs(start.children[ch], word[1:])
+        else:
+            return False